Shanghai-based Ctrip.com Inc has invested in U.S.-based supersonic airplane developer Boom Supersonic, which is developing next-generation airplanes to halve flight times from China to the United States, South Asia and Oceania.

The two companies will work together to bring Boom's still being developed Mach 2.2 airliner to China so that passengers can fly from Shanghai to San Francisco in 6 hours, down from the current 11 hours. The flight time between Beijing and Shanghai will shrink to 40 minutes from 2 hours now, the companies said.

"Ctrip is making a strategic investment in the next generation of travel," James Liang, the firm's co-founder and executive chairman, said in a statement as China's biggest online travel agency plans to diversify business to "all things related to travelling" through investment and globalization. No details of the investment have been released.

Boom is building a supersonic airliner capable of carrying 55 passengers at Mach 2.2, more than twice as fast as current passenger airplanes.

Boom Supersonic, whose other investors include 8VC, RRE, Lightbank and Y Combinator, has so far raised US million. Japan Airlines and Virgin Group are also touted as its potential customers.